In general, a plastic material is being applied to many products due to high workability and flexibility. However, the plastic material has deteriorated surface hardness, durability, fouling resistance, scratch resistance, gloss properties, and heat resistance, and thus needs to be double- or triple-coated with various coating materials on the surface in order to apply functionality depending on use of a plastic product.
For example, Korean Patent Publication No. 10-2006-0121334 relates to technology for forming an organic passivation film on a plastic surface and a metal passivation film at its outside, physically molding all the plastics in a vacuum chamber, again forming an organic passivation film on the surface and a metal passivation film at its outside, and realizing a variously colorful metal-like texture through physical and chemical deposition in the vacuum chamber, and discloses a method of surface-coating a plastic-molded article which includes: a washing process of washing all kinds of foreign particles remaining on the surface of the plastic-molded article by using compressed air and solvents and then drying it; an organic passivation film-forming process of forming a passivation film by coating an organic material having excellent adherence to an inorganic material and an excellent surface-curing property through spraying or dipping; a mineral passivation film-forming process of forming a passivation film by coating a mineral on the surface-cured plastic molded article through spraying or dipping to suppress elution of gas; and a vacuum-deposition process of forming a metal passivation film through physical and chemical deposition in a vacuum chamber to apply physical and chemical characteristics to the plastic molded article having a composite passivation film of alternative organic/metal passivation films and realize a variously-colorful metal-like texture, but has a problem of an extremely complex process and deteriorated durability and thermal stability of the coating layer. Further, Korean Patent Publication No. 10-2011-0014517 discloses a method of hard-coating a plastic by surface-coating it with a urethane-based polymer having an ethylenic unsaturated group in a molecule, a mass average molecular weight of 3000-200,000 when measured through gel permeation chromatography, and a glass transition temperature of greater than or equal to 30%, and a silica particle having an ethylenic unsaturated group, but still has a problem of insufficient surface hardness, fouling resistance, and thermal stability.
In addition, an attempt to improve surface hardness, fouling resistance, and thermal stability by forming a hard coating layer on a plastic substrate in various methods has been made, but there is a problem of insufficient adherence such as separation on the interface of the substrate, the hard coating layer, and the like, and Korean Patent Publication No. 10-2013-0100345 discloses a method of laminating a polycarbonate resin layer—an adhesive layer—a hard coating layer to form the hard coating layer on a transparent plastic film, but has a problem of a complex process, and has an additional problem of deterioration of properties such as heat resistance, chemical resistance, and the like due to separate formation of the adhesive layer.